1. Field of the Invention
This invention relates to an disc-shape recording medium. More particularly, it relates to a disc-shaped recording medium on which compressed audio PCM data are recorded and which may be advantageously employed in a small-sized portable disc recording/reproducing apparatus.
2. Summary of the Invention
The present invention provides a disc-shaped recording medium in which compressed audio data are recorded by optical means wherein, with the inner diameter of a data recording region of a disc being set to a predetermined value within a range of 28 to 50 mm, the outer diameter of the data recording region for inner diameter of said data recording region of 28 mm is set in a range from 58 to 82 mm and said outer diameter for said inner diameter of 60 mm is set in a range from 71 to 73 mm, whereby the recording medium may be used with a small-sized portable disc recording/reproducing apparatus and a playback time about as long as that of a standard 12 cm CD may be realized by recording compressed audio data having the compression rate of e.g. 1/4.